{"id":"CVE-2025-12999","revision":null,"records":[{"revision":"d9f5f82d15714c2887308ca9a1e3379a","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2025-12999","aliases":[],"title":"UrlUtil.getBaseUrl builds the absolute URLs in a response — download links, icons, asset and API URLs — from the X-Forwarded-Host, X-Forwarded-Proto and X-Forwarded-Prefix request headers, with no check on whether the sender was a trusted p…","description":"UrlUtil.getBaseUrl builds the absolute URLs in a response — download links, icons, asset and API URLs — from the X-Forwarded-Host, X-Forwarded-Proto and X-Forwarded-Prefix request headers, with no check on whether the sender was a trusted proxy, falling back to the client-supplied Host header.                                                                                   \n\n                                                                                                                                                                                              \n\n\nThose responses are cached under keys that do not include the host (extension.json since 0.6.0, namespace.details.json since 0.9.0, sitemap since 0.14.5, latest.extension.version.vscode since 0.34.2). A single request carrying a forged header therefore places attacker-chosen URLs into an entry served to every other client for the lifetime of that entry — one hour by default, and cluster-wide where ovsx.redis.enabled is set.\n\n\n\nThe VSIX download URL, its signature URL and the public key URL are all derived from the same base URL, so extension signing does not limit the impact: an attacker who poisons an entry supplies the package, the signature over it, and the key used to verify it.                                                                                    \n\n\n\nExploitability depends on deployment topology. A server reachable directly by clients, or fronted by a proxy that relays the client's X-Forwarded-Host rather than overwriting it, is exploitable by an unauthenticated remote attacker. A proxy that overwrites the header is not.\n\n\n\nAn unauthenticated attacker can poison Open VSX's per-extension metadata cache with attacker-controlled download, signature, and public-key URLs by supplying a crafted X-Forwarded-Host header, causing downstream VS Code-compatible editors to fetch and install a malicious VSIX.\n\n\n\nWorkarounds (unpatched versions)\n\n  \n\n\n1. Configure the reverse proxy to set rather than relay X-Forwarded-Host, X-Forwarded-Proto and X-Forwarded-Prefix — note that nginx's $host is the client's Host header and is not a safe value.\n\n\n\n2. Ensure the server is not reachable except through that proxy.\n\n\n\n3. Flush the caches afterwards; poisoned entries survive the configuration change.","state":0,"publishedAt":"2026-09-21T08:59:00.465+00:00","modifiedAt":"2026-09-30T15:09:36.585+00:00","affected":[{"ecosystem":"Vendor product","name":"Eclipse Open VSX","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"Eclipse Foundation\",\n                    \"product\": \"Eclipse Open VSX\",\n                    \"versions\": [\n                        {\n                            \"status\": \"affected\",\n                            \"version\": \"0.6.0\",\n                            \"lessThanOrEqual\": \"1.1.2\",\n                            \"versionType\": \"semver\"\n                        }\n                    ],\n                    \"defaultStatus\": \"unaffected\"\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:L/SC:H/SI:H/SA:H","score":9.1,"severity":"CRITICAL"}],"references":["https://github.com/eclipse-openvsx/openvsx/security/advisories/GHSA-f55q-5m46-rmxc","https://github.com/eclipse-openvsx/openvsx/pull/2196","https://gitlab.eclipse.org/security/cve-assignment/-/work_items/75"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2025-12999","license":"CVE Program Terms of Use","key":"cve-program:CVE-2025-12999","identifiers":["CVE-2025-12999"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. Missing entries do not establish absence of exploitation.","generation":"2026-11-12T03:56:46.1287087+00:00","complete":true,"records":1779,"lastAttemptAt":"2026-11-12T03:56:46.1287087+00:00","lastSuccessAt":"2026-11-12T03:56:46.266109+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:46.2661097+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"cve-program","scope":"Official CVE Program baseline and cumulative hourly delta; all vendors, published and rejected records","generation":"cve-64752486c567b55b31fb0d7225f5222bcd0019564ac0ac5f0649e242c7b19299-beddb039e9e8d22605e2eaa29616069a8dbcaa39d8913522266b856ccc773385","complete":true,"records":424562,"lastAttemptAt":"2026-11-12T03:56:45.0720206+00:00","lastSuccessAt":"2026-11-12T03:56:45.0520395+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.0720206+00:00","snapshotPublishedAt":"2026-11-12T03:29:06+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"euvd","scope":"Rolling EUVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global EUVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-83f01e9b693347759bbcba1498652358","complete":false,"records":13760,"lastAttemptAt":"2026-11-12T04:06:30.4778921+00:00","lastSuccessAt":"2026-11-12T04:06:30.473+00:00","error":"350 identifier lookups failed; latest failures include AccessDenied (HTTP 403). Other identifiers were checked independently.","lastVerifiedAt":"2026-11-12T04:06:30.473+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13463,"expectedIdentifiers":13813,"failedIdentifiers":350},{"source":"first-epss:nuget","scope":"FIRST EPSS for explicit CVE aliases in the collected public NuGet archive. Not a global EPSS backfill.","generation":"2026-11-12T03:56:46.1287087+00:00","complete":true,"records":1097,"lastAttemptAt":"2026-11-12T03:56:46.1287087+00:00","lastSuccessAt":"2026-11-12T03:56:46.2668013+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:46.2668014+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"nvd","scope":"Rolling NVD lookups of CVE aliases in current public OSV archives; 500 identifiers per refresh, rechecked after 48 hours. Not a global NVD catalog. Successful not-found lookups count as checked; they do not imply withdrawal or safety. No reader inventory is sent.","generation":"enrichment-52451a58cbcb4287967102045f86ce70","complete":true,"records":13760,"lastAttemptAt":"2026-11-12T03:56:47.5828253+00:00","lastSuccessAt":"2026-11-12T03:56:47.579+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:47.579+00:00","snapshotPublishedAt":null,"importing":false,"stagedRecords":0,"checkedIdentifiers":13813,"expectedIdentifiers":13813,"failedIdentifiers":0},{"source":"osv:Go","scope":"Complete OSV Go ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"go-3562b6c78fd1bd0f0b55daf66a0926ae24f65e462df7f6d928caad458fc696bf","complete":true,"records":9947,"lastAttemptAt":"2026-11-12T03:56:45.7079161+00:00","lastSuccessAt":"2026-11-11T04:27:43.6877707+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.7079161+00:00","snapshotPublishedAt":"2026-11-11T03:32:46+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:NuGet","scope":"Complete OSV NuGet ecosystem archive, including GitHub Advisory Database records; NuGet version matching only","generation":"nuget-456002455e0ab94bb92c95476d4e6d175c104cd594749982afd96c893728ecbc","complete":true,"records":2010,"lastAttemptAt":"2026-11-12T03:56:45.2248127+00:00","lastSuccessAt":"2026-11-11T02:36:58.1276999+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.2248127+00:00","snapshotPublishedAt":"2026-11-11T01:17:51+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:crates.io","scope":"Complete OSV crates.io ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"crates.io-baa8362b4daf9e5f39d5563775a55935e7b442c0735d33274a921579ce4a0d66","complete":true,"records":3093,"lastAttemptAt":"2026-11-12T03:56:46.0887439+00:00","lastSuccessAt":"2026-11-11T13:00:02.5446881+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:46.0887439+00:00","snapshotPublishedAt":"2026-11-11T12:47:47+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null},{"source":"osv:npm","scope":"Complete OSV npm ecosystem archive, including withdrawn and malicious-package source records; statement counts are not unique CVE counts","generation":"npm-685fe7fb2b690656c910a1ea42a9d294e8353311ac8ecfa691a9b0ff1b328804","complete":true,"records":231695,"lastAttemptAt":"2026-11-12T03:56:45.6007038+00:00","lastSuccessAt":"2026-11-11T21:58:47.7265713+00:00","error":null,"lastVerifiedAt":"2026-11-12T03:56:45.6007038+00:00","snapshotPublishedAt":"2026-11-11T21:48:35+00:00","importing":false,"stagedRecords":0,"checkedIdentifiers":null,"expectedIdentifiers":null,"failedIdentifiers":null}]}